1. Field of the Invention
The present invention relates to an Hypertext Transfer Protocol (HTTP) based video streaming apparatus and method, and particularly, to an HTTP-based video streaming apparatus and method that supports random access in a mobile communication system providing video streaming service based on HTTP.
2. Background of the Related Art
Generally, video on demand (VOD) in a mobile communication system is a service that receives content information desired by a user from a server and plays the information on a mobile communication terminal. VOD can be realized in an HTTP-based download method and an RTP-based streaming method.
The HTTP-based download method plays the content information after downloading all of the content information in the terminal to provide high quality multimedia service. However, the HTTP based method requires that the user wait a period of time in order to completely download the contents. Moreover, the terminal requires a large amount of storage space for the fully downloaded content.
The Real Time Protocol (RTP) based streaming method, on the other hand, plays the received contents after buffering at least a portion of the contents for a predetermined initial delay time. The user is thus able to receive and view the contents in real-time. However, the quality of the presentation of the content is limited due to the limitation in transmission bandwidth, and some of the data may be damaged due to the transmission environment.
An HTTP-based streaming method combines advantages of both the HTTP based download method and the RTP based streaming method.
FIG. 1 is a drawing illustrating a related art HTTP based streaming apparatus. The apparatus includes a storing disk 10 for storing content files transmitted from a server (not shown), and a display unit 12 for displaying the content files stored in the storing disk 10 by decoding them using a decoder 11 so that the user can view the contents. The apparatus further includes a random access searching unit 13 for searching a random access point requested by the user within the content files stored in the storing disk 10.
The random access searching unit 13 identifies whether there is a random access point required by the user in the content files stored in the storing disk 10, and decodes and plays from that point if the point is present in the content file.
The solid lines illustrated between the storing disk 10 and the decoder 11, between the decoder 11 and the display unit 12, and between the random access searching unit 13 and the storing disk 10 represent the signal flow for general HTTP streaming service, and the dotted lines represent a signal flow generated when random access is required by the user.
An operation of the related art HTTP-based streaming apparatus will be described as follows. First, transmission control protocol (TCP) packets, which are transmitted from a transmitting server, are stored in the storing disk 10 through a buffer by the receiving party. The storing disk 10 stores the received packets for a predetermined period of time in file form. The files stored for the predetermined delay time are then decoded and played on the display unit 12 so that the user can view them. At that time, the storing disk 10 continuously receives and stores the packets from the transmitting party server while the stored files are displayed.
When the user requires random access, the random access searching unit 13 searches the files stored in the storing disk 10 to determine whether the file stored in the storing disk 10 include the random access point. If the random access point is present in the file, the file is decoded and displayed on the display unit 12 from that point. On the contrary, if the required random access point is not in the files, the random access function is not supported.
The related art HTTP based streaming method has various problems. For example, as with the HTTP based download method in such viewpoints, port and data channel for transmitting the contents are set using HTTP, and TCP is used for transmitting the actual content packets. However, the HTTP based streaming method decodes and plays the received TCP packets after buffering them for a predetermined delay time, differently from the HTTP based download method in which the content files are played after transmitting the entire file from the server of the transmitting party to the receiving party.
Accordingly, the HTTP based streaming method has a disadvantage that the utility of the random access function is reduced to less than that of the RTP based streaming method.
Additionally, the related art HTTP based streaming method is only able to perform the random access function for the content file stored in the storing disk after being transmitted to the receiving party. That is, in order to identify certain contents by the user, the certain content file must already be stored in the storing disk of the receiving party.
Therefore, according to the related art HTTP based streaming method, even if the user wants to receive information from a certain multimedia content point when the streaming has started, the transmission from that point cannot be made.
Also, according to the related art HTTP based streaming method, if the random access requirement occurs during the streaming service, the random access function for the above requirement cannot be supported if the corresponding contents are not stored in the storing disk of the receiving party.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.